package com.infopatent.shldevtools.tools;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import org.apache.commons.codec.binary.Hex;
import org.apache.commons.codec.digest.DigestUtils;
import org.apache.log4j.LogManager;

/**
 *
 * @author shaohailong
 */

/**
 * 计算大文件MD5 值的工具类 网上对比了多个选择,这个是速度最快,用时最少的
 */
public class GetBigFileMD5Tools {
    private static final org.apache.log4j.Logger log = LogManager.getLogger(GetBigFileMD5Tools.class);
    static MessageDigest MD5 = null;

    static {
        try {
            MD5 = MessageDigest.getInstance("MD5");
        } catch (NoSuchAlgorithmException e) {
            log.error(e.getMessage(), e);
        }
    }

    /**
     * 对一个文件获取md5值
     *
     * @return md5串
     */
    public static synchronized String getMD5(File file) {
        FileInputStream fileInputStream = null;
        try {
            fileInputStream = new FileInputStream(file);
            byte[] buffer = new byte[8192];
            int length;
            while ((length = fileInputStream.read(buffer)) != -1) {
                MD5.update(buffer, 0, length);
            }


            return new String(Hex.encodeHex(MD5.digest()));
        } catch (FileNotFoundException e) {
            log.error(e.getMessage(),e);
            return null;
        } catch (IOException e) {
            log.error(e.getMessage(), e);
            return null;
        } finally {
            try {
                if (fileInputStream != null) {
                    fileInputStream.close();
                }
            } catch (IOException e) {
                log.error(e.getMessage(), e);
            }
        }
    }

    /**
     * 求一个字符串的md5值
     *
     * @param target 字符串
     * @return md5 value
     */
    public static String MD5(String target) {
        return DigestUtils.md5Hex(target);
    }

    public static void main(String[] args) {

        long beginTime = System.currentTimeMillis();
        File fileZIP = new File("D:/TEST/IMAGE2.zip");
        String md5 = getMD5(fileZIP);
        long endTime = System.currentTimeMillis();
        System.out.println("MD5:" + md5 + "\n time:" + ((endTime - beginTime) / 1000) + "s");
    }
}
